John H

If I have a 915 with a 26/26 5th gear and a 7/31 ring and pinion, what would my wheel speed be at 7000 rpm's? I am running 335/30/18 rears if that matters. I have no idea how to calculate this stuff. Thanks to anyone who can.

Professor Helmüt Tester

MPH = (RPM x tire diameter in inches) / (overall gear ratio x 336)

Kurt R

This site produces 121.84 mph, the same you would get from the professor's formula.

John H

Hmmm. That is weird. It sure seems like it should be higher than that. I guess I'll have to check the numbers again. Would a 25/26 gear be higher or lower.

does 26/26 equal 1.0?
does 7/31 equal 4.42?

I wasn't sure how to use the numbers in the Professor's formula.

Kurt R

25/26 would be 4% lower than a direct 5th.
yes and yes, well closer to 4.43 to the other two questions

John H

thanks guys.

John H

OK. Maybe I am a bit slow today but would a 24/27 gear be .8888 or 1.125 for the gear calculator linked above?